Any bag thickness guide starts with the fact that the bag industry never agreed on one way to measure thickness. Ask different suppliers for a quote and I can guarantee that you’ll get four different numbers, all different from one another with each supplier having a different reason.
That’s why in this blog, we’re covering a bag thickness guide you can follow so you don’t get lost. Once you know the right and best value for what you’re looking for, you can optimize, and then the real deal starts.
Why a Bag Thickness Guide Needs to Cover Four Systems
Before we begin, it’s imperative that you understand that there are different factors in determining bag Thickness. The confusing part is that these units aren’t just 4 different ways of saying the same thing.
Also Read: OEM Drawstring Bags Manufacturing Process: From Design To Bulk Production
In fact, they’re different and tell a distinct story. So a number that sounds high in one system can mean very little in another, and it can be not that important for that particular category, too. Let’s take a look at these things and find out each unit that belongs to which material.
| Measurement | Unit | What it weighs | Materials it is used for |
| GSM | Grams per square meter | The finished cloth | Non-woven, cotton, canvas, rPET |
| Ounce | Ounces per square yard | The finished cloth | Canvas and heavy cotton |
| Denier | Grams per 9,000 m of yarn | A single thread | Polyester, nylon |
| Micron or mil | Thousandths of a mm or inch | The film itself | PEVA, PVC, polyethylene |
Notice that only the last row measures thickness in the everyday sense. The other three are weights, and weight is a useful stand-in for thickness only when you are comparing like with like.
Bag Thickness Guide: The Four Measurements You Need to Know
This can get very confusing simply because different materials use different measurements. You can see fabric listed in GSM, while canvas in ounces. On the other end of the rope, you’ll see nylon in denier, and microns for plastic films. And that’s what we’ll be eliminating today! Here’s what each number actually tells you.
Bag GSM
For many fabric bags, weight is shown in grams per square meter. Whatever the value is will tell you how much one square meter of the material weighs. You’ll usually see GSM used for cotton, non-woven polypropylene, canvas, and recycled fabrics.
- Lower GSM: Usually lighter and thinner.
- Higher GSM: Usually heavier and more substantial.
- One thing to check: Coatings add weight too. A coated 120 GSM fabric may contain less actual cloth than an uncoated fabric with the same rating.
As a rough example, 70 GSM non-woven feels quite light, but those that have a 340 GSM cotton feels much heavier and fuller in the hand.
Canvas Ounce
In the United States, you’ll be able to buy canvas by ounces per square yard. So, when you see 12 oz canvas, it means one square yard of that material weighs 12 ounces.
- Around 8 oz: Light canvas for simpler bags.
- Around 12 oz: A stronger everyday weight.
- 16 oz and above: Thick, firm, and much heavier.
One detail is worth checking with the supplier because there are mills quote weight per linear yard instead. That’s not the same measurement because fabric width changes the result.
Read More: Drawstring Cord Materials Guide: Cotton Rope, PP Cord, and More!
Fabric Denier
With nylon and polyester, the number usually refers to the yarn rather than the finished cloth. For instance, a 9,000-meter measurement of a 600D yarn weighs 600 grams. In simple terms, a higher denier usually means a thicker yarn.
- 210D: Light and easy to fold.
- 420D: A useful middle weight for regular use.
- 600D: Heavier and better for repeated handling.
To be clear, this number doesn’t tell you how tightly the fabric is woven. Two fabrics marked 300D can still feel quite different.
NOTE: Very light polyester may use a T rating, such as 190T or 210T, instead. So, be careful and double-check everything before you sign or place an order.
Plastic Film Thickness
There’s no yarn to measure with plastic film, so the thickness itself is measured. Most markets use microns, while the United States may also use mils.
- 1 micron: 0.001 mm
- 1 mil: 0.001 inch, or about 25.4 microns
- 80 to 120 microns: A common range for garment covers and similar bags
Mils and microns are easy to mix up. A 4 mil film is about 102 microns thick, which is very far. They should never be compared as if the numbers mean the same thing. Again, you’d want to double-check and be sure of what you’re looking at so you avoid any problems in the future.
The key point in any bag thickness guide is that GSM, ounces, denier, and microns measure different things. Always check the unit before comparing one material with another.
Converting Between the Different Measurements
Are you trying to compare different bag materials? Do you want to do deeper research before making your purchase? If you do, congrats, because, that’s the right thing. In fact, most of these measurements are easy to convert. The only exception is denier and GSM, and we’ll dive deeper into that below.
The Easy Conversions
You only need a simple calculation for ounces, GSM, mils, and microns; it’s arithmetic and it’s something you’ll easily be able to solve inside your head.
| Convert | Calculation | Example |
| Ounces to GSM | Multiply by 33.9 | 12 oz ≈ 407 GSM |
| GSM to ounces | Divide by 33.9 | 340 GSM ≈ 10 oz |
| Mils to microns | Multiply by 25.4 | 4 mil ≈ 102 microns |
| Microns to mils | Divide by 25.4 | 120 microns ≈ 4.7 mil |
Why Denier Cannot Be Converted to GSM
There isn’t an exact formula for denier to GSM., and the reason is simple: the denier rating measures the yarn, while GSM measures the finished fabric. How tightly a yarn is woven changes the final weight and feel of the fabric.
A dense 300D fabric could even weigh more than a loosely woven 600D fabric.
So, if you need to compare fabrics that use different systems, ask the supplier for the GSM as well as the denier rating. You can also ask them for whatever system of measurement you prefer. That gives you a much clearer comparison and a better time to decide which one to go for.
Also Read: Cotton vs. Canvas vs. Polyester Drawstring Bags: Which Material Should Buyers Choose?
What These Values and Measurements Leave Out
Knowing the thickness of your fabric helps, it helps a ton. However, it doesn’t tell you the whole story. Two fabrics with the same number can still feel and work very differently.
Weave Density
A tight weave packs the threads closer together. This can make a lighter fabric feel stronger than a heavier fabric with a loose weave.
Coatings
A coating adds weight to the fabric. That means the GSM can go up even though there is no extra cloth.
Fiber Type
Cotton and polyester can have the same GSM but still feel very different. The type of fiber changes the softness, weight, and feel of the bag.
Reinforcement
Extra stitching can make a bag stronger without using thicker fabric. Reinforced handles are a good example.
Fabric Finish
Brushing or pressing the surface can change how the fabric feels. The weight may stay exactly the same.
This is why a physical sample still matters. Two fabrics marked 300 GSM may look similar on paper but feel completely different in your hands.
How to Check a Number Before Going With It
Numbers on a quote are useful, but it’s even better when you know the right and easiest way to check it.
Checking the GSM
GSM is fairly easy to test with a small fabric sample and a kitchen scale. You want to start by cutting a 10 cm × 10 cm squares and weigh them in grams. Then multiply that weight by 100. So, if the sample weighs about 3 grams, the fabric is close to 300 GSM.
A small difference is normal. But, if the result is more than about 10% lower than the quoted number, ask the supplier to explain to you what happened.
Checking the Plastic Film
Film thickness is easiest to check with calipers. If you don’t have calipers, stack several layers together and measure the total thickness. For example, if 10 layers equal 1 mm, each layer is about 100 microns thick.
This is only a rough check, but it can still show whether the film is close to what was quoted.
Checking the Denier
Denier is harder because it measures the yarn before the fabric is woven. You cannot reliably confirm it from a finished bag at home. Instead, ask the supplier for the mill specification. It should show the denier used in the fabric and, when needed, whether that number applies to the warp, the weft, or both.
Suppliers who know the material should be able to provide that information clearly.
Get the Right Quote From Wuxi Environment Package Co., Ltd!
When you finally understand and know what these values mean, bag quotes become easier to compare. Here at Wuxi Environment Package Co., Ltd., we’ll give you everything you need to know. We’ll never leave any important information out and we’ll be more than happy to help you with the right thickness.
This bag thickness guide gives you a simple way to read those numbers without guessing, but with our help, you no longer have to look elsewhere. We help buyers compare materials before ordering.
If two options look similar on paper, ask us fore the full specs and a sample, and we’ll be more than happy to give them to you. Get a free quote today!
